In today’s intensely competitive global market, product enterprises are constantly seeking new ways to shorten lead times for new product developments that meet all customer expectations. In general, product enterprise has invested in CAD/CAM, rapid prototyping, and a range of new technologies that provide business benefits. Nowadays, reverse engineering (RE) is considered one of the technologies that provide business benefits by shortening the product development cycle . Figure 1, shows how reverse engineering can close the gap between what is “as designed” and what is “actually manufactured” .
Reverse engineering (RE) is now recognized as an important factor in the product design process which highlights inverse methods, deduction and discovery in design. In mechanical engineering, RE has evolved from capturing technical product data, and initiating the manual redesign procedure while enabling efficient concurrency benchmarking into a more elaborated process based on advanced computational models and modern digitizing technologies . Today the application of RE is used to produce 3D digital models of various mechanical worn or broken parts. The main steps in any reverse engineering procedure are: sensing the geometry of the existing object; creating a 3D model; and manufacturing by using an appropriate CAD/CAM system . Read More
Despite the deepening understanding of the essence of gas-dynamic processes and the development of computational methods, simpler design methods such as scaling and trimming remain in demand in turbomachinery engineering. The main advantage of these approaches over design from scratch is simplicity and its inexpensive nature due to the small-time expenditure and lower demand from computational resources. Good predictive accuracy of the performance and efficiency of the resulting machines is based on the use of an existing machine with well-known characteristics as a prototype.
Conversely, using the prototype imposes restrictions on the use of scaling and trimming methods. It is almost impossible to get a new design with pressure and efficiency higher than that of the prototype. Also, in cases where it is required to obtain performance that is significantly different from the prototype, the inherent reliability of the original prediction may be insufficient.
Easy to apply and general, valid, scaling laws are needed for design and application engineers. The scaling laws are needed for the purposes of:
Predicting the full-scale performance machine from model test data obtained from a scaled machine
Obtaining a family of machines with different performances on the basis of one well-tested machine
Experimental performance and efficiency testing on a full-size model of large machines such as fans to ventilate tunnels and mines or to move combustion air and smoke gas in power plants may be impractical due to the high energy costs and geometric limitations of the experimental stand. In these cases, a scale model is used. And although complete similarity is not maintained, for example, in terms of the Reynolds number, the correction factors in most cases are well known and the prediction accuracy is high.
The method involves the implementation of the flow path of the designed fan or compressor on a scale to the prototype. This means that all linear dimensions (e.g. diameters, blade chord, axial length, etc.) must be multiplied by the scaling factor (SF). The angular dimensions (e.g. blade angles at inlet and outlet, stagger angle, etc.) remain unchanged.
When scaling, it is assumed that parameters such as Pressure Ratio, circumferential velocity (U), and axial velocity (Cz) are equal for the designed machine and the prototype. Thus:
The condition of equality of the Reynolds criteria is not ensured, since the designed compressor and the prototype do not have the same diameters of the rotor with the equality of other parameters that determine the number of Rew. This design guarantees the practical accuracy of the calculated characteristics, provided that the gas movement in the flow path is turbulent. It is known that for “physical” values of the Reynolds numbers
the flow remains turbulent and the inequality of the Reynolds numbers of the designed compressor and the prototype has little effect on the gas-dynamic characteristics.
To determine the efficiency of low-pressure fans, a well-known formula is usually used:
An example of obtaining a stage of an axial compressor by the scaling method is shown in Figure 1.
The disadvantages of the scaling method include the need to change the rotor speed. This can be relevant for industrial installations, where the rotation speed is often limited and tied to the frequency of the electrical network current. Additionally, the need to change the overall dimensions can be a limiting factor, especially if it is necessary to increase productivity significantly, and the installation location for the turbomachine is limited. In some cases, maintaining full geometric similarity is impossible for technological or constructive reasons. For example, the minimum value of the tip clearance may be limited by the operating conditions of the rotor (not touching the rotor against the housing) or the impossibility of obtaining a small clearance if the scaling is carried out from a large prototype to a small model.
Centrifugal Compressors are the turbomachines also known as turbo-compressors, and belong to the roto-dynamic class of compressors. In these compressors the required pressure rise takes place due to the continuous conversion of angular momentum imparted to the working fluid by a high-speed impeller into pressure. These compressors are used in small gas-turbines, turbochargers, chiller units, in the process and paper industries, oil & gas industries and others.
The design and manufacturing of such compressors are always challenging because of its 3-dimensional shapes, high rotational speeds that interact with different loss mechanisms, and stringent working environments. In many circumstances, it is necessary to analyze an existing compressor, with the end goal being to redesign it, enhance its performance, or to use it in completely different applications. In order to meet such requirements, reverse engineering is a viable option. With reverse engineering, one can review competitor’s design to remain in market competition.
Reverse engineering allows us to collect incomplete or non-existing design data and manufacture an accurate recreation, safely, of the original product or component.
Sometimes, it is also referred to as back engineering, in which centrifugal compressors or any other product are deconstructed to extract design information from them. Oftentimes, reverse engineering involves deconstructing individual components like the impeller or diffuser of larger compressors. End-users often use this approach when purchasing a replacement impeller or any other compressor part from an OEM is not an option. In some cases, where older impellers that have not been manufactured for 20 years or more, the original 2D drawings are no longer available. When this is the case, the only way to obtain the design of an original compressor is through reverse engineering.
Reverse engineering requires a series of steps to gather precise information on a product’s dimensions. Once collected, the data can be stored in digital archives. Figure 1 (left) shows the typical process of reverse engineering. In figure 1 (right), one can see the scanning process of the centrifugal impeller using a laser scanner.
To reverse engineer an impeller or any other part of compressor, an organization will typically acquire the component and take it apart to examine its internal mechanisms. This way, engineers can unveil information about the original design and construction of the product. One can start by analyzing the dimensions and attributes of the impeller and make measurements of the blade widths, diameters and angles, as these dimensions often relate to the compressor’s performance. Read More
Landspeeders belong to the “repulsorlift” transport class, like the podracers we looked at last year, and travel above a world’s surface (up to 2 meters) without contact (very useful on swampy lands like Dagobah). Landspeeders are the successors to the hanno speeder which was mainly used as a racing vehicle with many Tatooine natives still using them to race in the Boona Eve Classic today.
Landspeeders are found in both civilian and military applications but due to intergalactic ITAR regulations we will only cover the civil aspect here with a focus on the most famous of them all. If you want to know more about our experience working with military, defense and governmental organizations (whether you area part of the Empire, Rebels, Resistance or Separatists) feel free to contact us.
The Famous X-34
Luke Skywalker’s X-34, with its 6 selectable hover heights, features an engine consisting of 3 air-cooled thrust gas turbines able to reach a top speed of about 155 mph. The side engines are also used for steering although it is not obvious whether this steering is achieved by varying their thrust to be asymmetric or through vectoring of their exhaust. With the X-34 total length being 3.4 meters it helps us estimate the overall dimensions of its engines which are, each, roughly 80 cm long by 30 cm wide. Read More
The typical life cycle cost of an industrial pump depends on its maintenance and energy consumption. Hence, it is necessary to keep track of the pump performance and do periodic maintenance to achieve performance level close to the performance predicted by the manufacturer. There are many instances in which maintenance becomes very costly to achieve the required performance. This is the point when owners must decide about whether to upgrading the system. Figure 1 shows the life cycle cost of typical industrial pumps.
In recent years, there have been many innovations in implementing newer materials as well as improvements in hydraulics. Improving pump designs is an ongoing process with designers looking for increasing performance by a few percentage points. The goal of the present pump manufacturers is to offer higher efficiency and reliability, but replacing an older pumps with newer pumps can mean higher costs. The focus for replacing the internals of the pumps with improved design has gained prominence since many of the components, like the casing and rotor, of the existing pumps can be reused. So instead of replacing the entire pump, it can be upgraded or retrofitted. When it comes to an upgrade, the first thing that should be considered is the return on investment which includes the initial investment, operating costs, and the reduction in energy consumption due to the improved pump performance.
Ever since circa 100 BBY, Podracing in its modern version has drawn crowds from far far away to watch pilots compete in races like the Boonta Eve Classic which made Anakin Skywalker famous and won him his freedom. By beating Sebulba, the Dug, and the other Podracers, Anakin became the first human to be successful at this very dangerous sport. The Force helped him in his victory by sharpening his reflexes, but his repulsorcraft was also superior due to its size and the modifications made to its twin Radon-Ulzer 620C engines, especially the fuel atomizer and distribution system with its multiple igniters which makes them run similarly to afterburners seen on some military planes on Earth.
Let’s take a deeper look at what repulsorcrafts are and how we can help Anakin redesign his to gain an even better advantage against the competition, provided that Watto has the correct equipment in his junk yard. Read More
One of the challenges of maintaining infrastructure is deciding how best to keep the operational costs in check while delivering the highest amount of service. This is especially true for aging equipment. One option is to replace the equipment with a newer version entirely, continue to maintain the existing machine, or a third option, retrofit the current machine with updated features.
Retrofitting is a term used in the manufacturing industry to describe how new or updated parts are fitted to old or outdated assemblies to improve function, efficiency or additional features unavailable in the earlier versions.
Retrofitting, like any investment of capital requires careful thought. SoftInWay’s Manage ring Director, Abdul Nassar has put together a simple list of questions to ask yourself before committing to a retrofit project. Answering these seven questions before you start can save you considerable time and effort. Read More
Reverse Engineering, or back engineering, is a term used for the process of examining an object to see how it works in order to duplicate or enhance the object when you don’t have the original drawings/models or manufacturing information about an object.
There are two major reasons reverse engineering is used:
create replacement parts to maintain the function of older machines;
improve the function of existing machines while meeting all existing constraints.
Reverse engineering is extremely important in turbomachinery for replacement parts in turbines or compressors which have been operating for many years. Documentation, reports and drawings for a significant amount of these machines is not available due to a variety of reasons, therefore keeping these important machines running is a challenge. One of the options to deal with this issue is to buy the modern analogue of the machine, which is not always feasible due to economic constraints or that there is no replacement available. Reverse engineering of the worn out parts might be the best option in the majority of cases.
In any case, the process to recovery original geometry of the object is the first and major step for all reverse engineering projects, whether you want just replacing/replicate parts or proceed with an upgrade to the machine.
Basic Steps to Any Reverse Engineering Project
Any reverse engineering process consist of the following phases:
Data collection: The object needs to be taken apart and studied. Starting in ancient times, items were disassembles and careful hand measurements were taken to replicate items. Today, we employ advanced laser scanning tool and 3D modeling techniques to record the required information in addition to any existing documentation, drawings or reports which exists.
Data processing: Once you have the data, it needs to be converted to useful information. Computers are essential for this stage as it can involve the processing of billions of coordinates of data converting this information into 2D drawings or 3D models by utilizing CAD systems.
Data modeling: This step was not available in beginning of reverse engineering. People just tried to replicate and manufacture a similar object based on the available data. Nowadays, engineers can utilize digital modelling, which represents all details of the geometrical and operational conditions of the object through a range of operation regimes. Typically, performance analysis and structural evaluation are done at this stage, by utilizing thermo/aerodynamic analytical tool, including 3D CFD and FEA approaches.
Improvement/redesign of the object: If required, this is the step where innovations can be created to improve the effectiveness of the object based on the collected data about the object’s geometry and operation.
Manufacturing: After the part is been modeled and meets the design requirements, the object can be manufactured to replace a worn out part, or to provide increased functionality.
Reverse Engineering in Today’s World
It very common to find the situations where reverse engineering is necessary for parts replacement, particularly with turbomachinery – steam or gas turbines, compressors and pumps. Many of these machines have been in operation for many years and experienced damaging effects of use over that time – like water droplets and solid particles erosion, corrosion, foreign objects, and unexpected operating conditions. Besides these expected needed repairs, some other reasons for reverse engineering might arise from a components part failure, as well as part alterations needed due to previous overhauls and re-rates.
All the conditions mentioned above require not only recovering the original geometry but also an understanding of the unit’s history, material properties and current operating conditions.
This article focuses on reverse engineering objects which have experienced significant change in their geometry due to the challenges of long term operation and their shape could not be directly recovered by traditional methods – like direct measurement or laser scanning. Pictures below are examples of such objects – steam turbines blading with significant damage of the airfoils with different causes such as mechanical, water/solid particle erosion, and deposit.
In the situations shown above, recovering the original geometry may be impossible if an engineer only has the undamaged portion of original part to work with. Which means that relying on undamaged portion of an original part it may be impossible to recover the needed portion due to significant level of damage.
Looking at the eroded turbine blading in Figure 1, recovering these airfoils with sufficient accuracy based on only a scan of the original part, would be very difficult, if not impossible, considering that 1/3 to ½ of the needed profile is wiped out by erosion.
In order to recover the full airfoil shape for turbines / compressors / or pumps blading, the information about flow conditions – angles, velocities, pressure, temperature – is required to recreate the airfoils profiles and a complete 3D blade.
In many cases with significant blading damage, the information obtained from aero/thermodynamic analysis is the only source of the information available for a designer and the only possible way to recover turbomachinery blading. In fact, in such a situation, the new variant of the airfoils is developed based on aero/thermodynamic information and by considering the remaining portion of the part, which would be the most accurate representation of the original variant. A structural evaluation should also be performed for any recovered part to ensure blading structural reliability in addition to the aero/thermodynamic study.
All of these engineering steps require employment of dedicated engineering design and analysis tools, which can perform:
– Accurate modelling of the turbo machinery flow path,
– 1D/2D aero/thermodynamic analysis and in some cases 3D CFD,
– Profiling and 3D staking of the blading,
– Structural evaluation, including 3D FEA tools.
SoftInWay’s team offers a comprehensive set of turbomachinery design and analysis tools within the integrated AxSTREAM® platform, which covers many steps, required for reverse engineering activities.
In Figure 6 below, a process diagram shows how AxSTREAM® products are used for reverse engineering.
After data collection, most of the geometry recovering steps are processed by AxSTREAM® modules:
– AxSLICE™ to process original geometry data, available from the scanned cloud of points.
– AxSTREAM® solver to perform 1D/2D aero/thermodynamic
– AxSTREAM® profiler to recover profile shape and 3D airfoil stacking.
– AxSTRESS™ for structural evaluation and 3D design.
– AxCFD™ for detailed aerodynamic analysis and performance evaluation.
Geometry recovered in this way is now ready to be used to develop detailed 3D CAD models and 2D drawings for further technological and/or manufacturing processing.
As an example of such capabilities, Figure 7 demonstrates the reverse engineering process for the 1000 mm last stage of 200 MW steam turbine with significantly damaged blades due to water erosion.
It is possible to recognize and extract the profile angles with a specialized tool – AxSLICE™, obtain slices on the desired number of sections and insert the extracted geometric data to an AxSTREAM® project.
The AxSTREAM® platform can provide seamless reverse engineering process for all components of complex turbomachinery.
Meet an Expert!
Dr. Boris Frolov has over 35 years of experience in steam/gas turbines design, analysis and testing. Earning his PhD in turbine stages optimization with controlled reaction, he is an expert in steam turbines aerodynamics and long buckets aeromechanics. Dr. Frolov has over 50 publications and 7 registered patents and he shares this vast knowledge as a lecturer in steam turbines, gas dynamics and thermodynamics for students studying power engineering sciences.
Steam turbine technology has advanced significantly since it was first developed by Sir Charles Parson in 1884 . The concept of impulse steam turbines was first demonstrated by Karl Gustaf Patrik de Laval in 1887. A pressure compounded steam turbine based on in de laval principle was developed by Auguste Rateau in 1896. Westinghouse was one of the earliest licensee for manufacturing steam turbines obtained from Sir Charles Parson and became one of the earliest Original Equipment Manufacturers (OEM) in power generation and transmission.
Over the years, as steam turbine technology advanced, the design principles were based on either impulse type or reaction type with reaction type being more efficient. Though impulse was not as efficient as reaction type, it gained popularity due to lower cost and compact size. With advances in design and optimization methods being employed, the efficiency levels between these two types are not very distant, ranging between 2 – 5% based on the size and application. Read More
Often, service companies are faced with the challenge of redesigning existing pumps that have failed in the field with extremely quick turnaround times. While there are quick-fix methods to return these pumps into operation, other more complex problems may require taking a step back and analyzing how this particular pump could be redesigned based on its current operation. These engineering upgrades could solve recurring issues with failure modes of a certain machine, and they could also solve new capacity demands that are imposed by a customer based on their system’s upstream or downstream changes. While efficiency increases could be beneficial to the overall system, many times it is more important to solve capacity requirements and increase the life of the pump by decreasing the Net Positive Suction Head Required (NPSHr).
In this blog post, we will investigate how to move an existing centrifugal pump through the AxSTREAM platform in order to solve engineering challenges seen on common OEM pump upgrades. With the use of AxSTREAM’s integrated platform and reverse engineering module, many of the CAE tasks that are common in an analysis such as this one can be realized in record speed. The first step of the reverse engineering process occurs in obtaining the necessary geometrical information for the desired pump. Through AxSLICE, the user can take an STL, IGES, CURVE file, or a generated cloud of points and properly transform this 3D profile into a workable geometry inside the AxSTREAM platform. In a matter of minutes, the user can outline the hub and shroud and transform a blank 3D profile into a profile defined by a series of segments. Seen in Figure 1, the centrifugal pump is now defined by a hub, shroud, and intermediate section.
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